When printing books and calendars, the subject matter at times is printed on sheets substantially wider than the eventual format. The paper being handled on which the print is applied, as well as the printing and subsequent processing, especially folding of a plurality of webs or plies of paper, can be similar to newspaper printing. There are some differences, however, since the respective single webs or plies, during movement over individual folders, have to be guided accurately until the combination sheets or webs or plies are supplied to a cutter. It is important that the sheets be fed free of creases, and without any relative shift or offset. This is particularly important if special cuts are to be made, for example index cuts, for thumb-indexing, for alphabetical, weekly or monthly indexing, or other marking. Such cuts or markers must be applied accurately with respect to the particular printed subject matter. There is a further difference between book and calendar printing and newspaper printing: Not only is there a difference in format and the variety of paper which is being used, but also the marked difference of the substantially lower number of signatures which are being printed than on newspaper presses.
The referenced German Patent 25 12 368, Kuhnberger et al, describes a folder which has two longitudinal folder apparatus. A device to apply a cross cut and a cross fold is located between the two folders. A collecting system is also provided. The format and the number of pages to be handled can be changed. It has been found that the cross folding results in a bending of the printed material and, upon collection, the folded printed product is bent. A relative shift of the printing products, that is, of the layers of the printed products, may result.
European Patent 0 019 202, Lange, describes a folding system which permits formation of a double cross fold, besides other possibilities of folding. This arrangement permits wide flexibility and the formation of the folds which are frequently required. It does not, however, solve the problem of possible shift of the respective layers of the webs or plies of the webs with respect to each other.
The referenced U.S. Pat. No. 4,779,859, Knauer, assigned to the assignee of the present application, and the disclosure of which is hereby incorporated by reference, describes a longitudinal folding system which has a folding triangle or folding funnel which can be changed and repositioned by shifting the folding triangle in the direction of the inclination thereof. This arrangement is particularly suitable to generate printed products of different formats and has the advantage that the wrap angle, with which the web surrounds the folder supply or run-on roller, in advance of the folding triangle, remains the same even if the folding triangle or former is shifted. Thus, even upon shift of the folding triangle, the tension relationships with respect to the running web does not change. The system requires a good deal of space and, if two such folders are to be placed sequentially behind each other, in the path of travel of the running web, the space requirement to generate a double parallel fold, at times, cannot be met.